Mirror/optics HELP? Is this all the parts i will need? alignment/placement?

[superbert]

Im still pretty unclear about which optics ill for a RGB setup.. can someone verify that these parts are what i will need to get a scanner setup? or am i missing something?:



-> scanning kit (scanners/drivers, PSU, scanner mounting block, interconnect cables)

-> OPTICS.... MOST CONFUSED ABOUT THIS PART
- 3 dichroic filters (pass green/pass blue/pass red)
- mirrors (broadband dielectric white light mirror/front surface mirror) **explanations of each? **how many? **placement?
- where do the beam splitters come into play?


any pics of a complete system with everything inside labeled would be extremely helpful. I dont necessarily need a step by step instructional session, as helpful as a how-to would be, but i can probably toy with things enough until they work (as long as i know i have everything).

[sugeek]

Take a look at the attached PDF and let me know if helps a bit.

-Adam

[buffo]

can someone verify that these parts are what i will need to get a scanner setup?

Sure. It's fairly easy if you think the process through first. (It helps if you draw your layout on a piece of paper first...)

OK, first you need a set of scanners. And yes, they come as a set, and will include the two galvos, the mounting block for the galvos, the scanner amps (one for each galvo), and a power supply for the amps. The set should also include the cabling to connect the power supply to the amps, and the cables to connect the amps to the galvos. You will need to connect the X and Y signals from the ILDA connector to the inputs on the amps. Most sets come with "pigtail" connectors (bare wire on one end, and a connector on the other) to make this easier, but you can wire it yourself if need be.

Now for the optics... You will be mixing the beams from 3 lasers. That means you only need 2 dichros. As for which type of dichro you need, that depends on how you want to arrange the lasers inside your projector.

A common arrangement is to have the green laser firing straight into the scanners, and then mix in the red and blue beams along the path of the green beam. In this case, usually the red is mixed in first (which means you need a pass-green, reflect-red dichro), and then the blue is mixed in last (which requires a pass-green-and-red, reflect-blue dichro). The reason for this arrangement is that blue photons are expensive, so you want them at the end of the chain, where they have to pass through the fewest optical elements. Here's a picture of what I'm talking about. (Ignore the pair of red beams at the top. They are combined with a PBS cube that is out of sight in this picture, and that's not something you'll need to worry about anyway. The beam path is what's important.)



However, you don't have to use this arrangement. You could put the red laser first, and the green laser second. Then you would need a dichro that reflects green and passes red. (Exactly the opposite of the layout above.) Of course, the blue dichro would stay the same. Here is a picture (from Loopee's gallery) that shows this layout:



Now, beyond the parts we've already discussed, you'll need a metal plate to mount everything onto. You'll also need to decide how you're going to supply power to the lasers. Most laser modules come with a power supply that runs of 120VAC power. In most cases, the output is 5 volts DC, which is fed to the laser driver module. You could install all three AC power supplies inside your projector case, but most people simply buy a beefy 5 volt power supply and run all 3 lasers off it. (You can even use an old computer power supply.) Also, you'll probably want to install a shutter at some point to block the beam. (This is a safety device that is strongly recommended.)

Now, as for broadband whitelight mirrors, there is no need for any of these unless you want to use a more complex optical path. Why would you want to do this? Well, if you bounce each beam before it hits the dichro, you can use the 1st bounce to perform near-field alignment (which is where the beams overlap at the face of the dichro) and then use the mount on the dichro itself to adjust your far-field alignment (which is where the beams overlap on the wall). With that extra bounce, alignment is very easy. (Without it, you have to physically move the lasers and/or shim them up or down to get the near field alignment correct.)

Note that alignment is something you should only have to do once, which is why most people simply play with the mounts of the lasers until they get it right. But adding another bounce does make things easier. Here is a somewhat cumbersome layout diagram that illustrates what this would look like. (The odd placement of the lasers in the diagram is because of some space considerations in this particular projector.)



Finally, to answer you last question (about beam splitters), you need to understand that having two red lasers is not a requirement. The only reason would be to get more power. Now, the problem with having two lasers of exactly the same wavelength is: How do you combine the beams? You can't use a dichro, because a dichro reflects one wavelength while passing another. If the wavelengths are the same it won't work. (It will either reflect both beams or pass both beams.) But there's a little optical trick you can exploit to combine the two beams anyway...

Many lasers have polarized output. And there is a common optical device known as a polarizing beam-splitting cube (or PBS, for short). It's a cube that splits an incomming beam into it's horizontally and vertically polarized components. We simply reverse that process. We seond a horizontally polarized beam from one laser into one face of the cube, and a vertically polarized beam from another laser into the other face, and the two beams are combined into a randomly polarized output beam that has (roughly) twice the output power.

Note that aligning the two beams using a cube requires the same alignment adjustments that you have for the different color beams. You have to get the near field correct (where the two beams meet on the diagonal face inside the cube), and you also have to get the far field correct (where the beams overlap on the wall). Thus most of the dual-red layouts will have adjustments on the bounce mirror that sends the 2nd beam into the cube (and this adjustment is used for near field corrections) as well as adjustments on the PBS cube mount itself (which is the far field adjustment).

If you're still confused, you might want to do a search here on PL for terms like "alignment" and "projector layout" to get more background information. Also, I strongly urge you to draw a diagram of what your projector will look like before you start buying things. And *especially* before you start assembling parts, be sure you have a plan to follow so you'll know that everything will fit. You'd be surprised at how quickly you run out of space inside a projector enclosure...

Adam

[superbert]

Ok, so now that I think i have enough to look at and contact info for help if i need it when i get started, whats involved with having my system certified for public use? Does the unit need to be checked by an organization (ILDA?), or do i just get myself a variance for my person? If it is the unit and not myself that requires the variance, I assume that each scanner that I build requires one?

Ive been looking at the enclosures here and see that some of them even include certification labels, but would really prefer to built one for cost purposes.. Is there a site that offers similar enclosures w/ certification that would be cheaper overall compared to building one and having it certified myself?

I have some friends that run a couple very popular clubs downtown, but they have no lasers and are interested in getting some together. Once my system passes all regulations and I have my legal variances/certifications in order, are the venues required to have one for me to use my system, or will my presence during their use suffice?

Thanks in advance guys! youve been a major help already!

[mccarrot]

If you fill in you profile page we can see were you are comming from and we could give you some local advise.

[superbert]

Im in central texas

[buffo]

Ok, so now that I think i have enough to look at and contact info for help if i need it when i get started, whats involved with having my system certified for public use?

You need to file a laser product report with the CDRH. Then you need to apply for a laser light show variance. Assuming all goes well, in a few months you'll be legal. Search the forums here for "CDRH Variance" and you'll get tons of good info on the topic.

A good place to start would be reading up on the relevant standards, which would be 21 CFR 1040.10 and .11 You'll want to understand these requirements extremely well before attempting to certify your projector. (It will also make things easier when you're building the projector if you can build it to spec to start with, rather than having to modify it later to add safety features required by the CDRH.)

I assume that each scanner that I build requires one?

Correct. However, if you are careful about how you fill out the product report, you can group a bunch of similar projectors together into a "class" of projectors that are all covered by a single laser product report. Likewise, it is wise to write your light show variance to encompass shows that have one, two, or three projectors in various configurations to allow you to perform several different types of shows.

Is there a site that offers similar enclosures w/ certification that would be cheaper overall compared to building one and having it certified myself?

Buying a pre-certified enclosure is always going to be expensive. Very expensive. If cost is an issue, you're far better off certifying it yourself - even if you start with a pre-assembled (but un-certified) housing.

I have some friends that run a couple very popular clubs downtown, but they have no lasers and are interested in getting some together. Once my system passes all regulations and I have my legal variances/certifications in order, are the venues required to have one for me to use my system, or will my presence during their use suffice?

The variance is for the show, not the venue. So yes, if your equipment is certified and you have an approved show variance, you can perform a show at the nightclub. Note that it must be you, or another "trained laserist" operating the projector. You can't have some cocktail waitress monitor the panel while you go outside to smoke a cigarette or take a piss...

The variance also assumes that you are using a certified projector(s). The accession number for the certified projector has to be listed in the variance. But so long as you apply for what is known as a "traveling variance" (that is, a laser show that is set up in several different locations), you will be able to set up your laser for a commercial show just about anyplace.

Of course, you still need to abide by the rules, and in some cases a low ceiling will prevent you from being able to set up the projector at all. (Beams can not be any lower than 3 meters off the highest point in the audience. So any room with an 8 ft ceiling is out.) Also, some states (New York and Arizona, for example) have special laws when it comes to laser shows and laser operators. You'll need to check with your local authorities on this.

If you're going to do commercial shows, you might want to think about taking a laser safety course from one of the companies that offer this sort of thing. Another good idea would be to join ILDA and attend a conference or two. You can really learn a lot that way, from the experts who are in the business of laser shows. Then too, the current ILDA president (Tim Walsh) is located in Texas - perhaps you could look him up and meet with him for a little Q & A session over a cup of coffee sometime...

Adam